Origins of neutrino events with three muons

The experimental observation of events in neutrino scattering with three outgoing muons presents a potential challenge to S${\mathrm{U}}_2$×${\mathrm{U}}_1$ gauge models, depending on the source of such events. In this paper a comprehensive study is reported of four possible modes of trimuon production (hadronic, mixed, leptonic, and trident modes). Background sources are expected to be significant and will have to be separated from other sources. Attention is also given to two trimuon events with extraordinarily energetic muons.